(a) Field of the Invention
The present invention relates to a liquid crystal display and a thin film transistor substrate for a liquid crystal display.
(b) Description of the Related Art
Liquid crystal displays typically include a first substrate on which are formed a common electrode and a color filter, and a second substrate on which are formed thin film transistors and pixel electrodes. The first and second substrates are provided substantially in parallel with a predetermined gap therebetween, and liquid crystal material is injected between the two opposing substrates. An electric field is formed between the substrates by applying voltages of different potentials to the pixel electrodes and common electrodes. Accordingly, the alignment of liquid crystal molecules of the liquid crystal material varies to control the transmittance of incident light.
However, a serious drawback of LCDs is their limited viewing angle. Various methods and configurations have been developed in an attempt to overcome this problem. In one such method, the liquid crystal molecules are aligned perpendicularly to the first and second substrates, and either a predetermined aperture pattern is formed in or protrusions are formed on the pixel electrodes and the opposing common electrodes. In some instances both a predetermined aperture pattern and protrusions are formed. Such methods are described in various papers including “A New Design to Improve Performance and Simplify the Manufacturing Process of High-Quality MVA TFT-LCD Panels” (Y. Tanaka, et al., 1999 SID, 16.5L) and “Ridge and Fringe-Field Multi-Domain Homeotropic LCD” (A. Lien, et al., 1999 SID, 44.1L).
However, as a result of the additional processes required to form the aperture patterns and protrusions, decreasing the productivity. Accordingly, in the case where protrusions are preferred, there is a need for a method in which apertures can be formed without performing supplementary processes. Further, there is the need for the formation of protrusions that can function to provide all the necessary characteristics for increasing the viewing angle of the LCD.
Another drawback of conventional LCDs is the frequent severing of wiring—gate lines, which transmit scanning signals, and data lines, which transmit image signals—in the thin film transistor substrate when manufacturing the same. To prevent this, redundant wiring is formed. The data wiring forms its redundant wiring by forming a transparent electrode layer, which is provided according to the layout of the data lines, when forming the pixel electrodes. When forming contact holes for the electrical connection between drain electrodes and the pixel electrodes, contact holes are also provided over the data lines. The redundant data wiring is connected to the data lines through these contact holes provided over the data lines.
However, circuits are shorted between the exposed redundant data wiring and the common electrode of the upper substrate if conductive particles come between these two elements. The formation of the aperture pattern or protrusions may cause this problem.